Modeling shear‐induced CHO cell damage in a rotary positive displacement pump

Abstract

Rotary lobe pumps are commonly used in the biotechnology industry for a variety of purposes. Shear damage to animal cells within the rotary lobe pump can adversely affect the product yield or purity during, for example, cell concentration via cross-flow filtration. In this research, CHO cells grown in 20-L bioreactors were fed to a rotary lobe pump in both single pass and recycle experiments were conducted at different RPMs and "slip" conditions. The results indicate that the slip flow rate more severely impacts the viability of the CHO cells than the pump RPM. A novel mathematical modeling approach is presented that predicts shear rates in all of the positive displacement pump's slip regions, and then predicts cell death vs. operating conditions. This model accounts for the complex flow situation that results from changes to RPM, backpressure and pump geometry (i.e., clearances).

Development of a small‐scale rotary lobe‐pump cell culture model for examining cell damage in large‐scale N‐1 seed perfusion process

“…We observed higher back pressures and lower flow rate at the same pump rate, which suggested there was higher back pressure, potentially driving more flow in the backward direction. This backflow of cell culture primarily traveled through the tight lobe clearances at high velocities and generated much higher shear relative to the shear calculated in the hollow fiber or piping 12 . Compiling all the damage data, regardless of the tubing ID within the bench‐scale pump setup, a damage threshold was seen around 3–4 psi.…”

“…This backflow of cell culture primarily traveled through the tight lobe clearances at high velocities and generated much higher shear relative to the shear calculated in the hollow fiber or piping. 12…”

“…The instant mitigation was to lower the pump rate to decrease the potential shear in the perfusion skid, given that the lower the pump rate, the lower chance to cause cell damage. 12,13 After reducing the flow rate, cell damage was subse- We thus developed a bench-scale robustness model to investigate potential cell damage through the rotary lobe pump. Flow rate, pressure and pump rates were recorded to characterize the pump performance.…”

“…Shear rate was aligned across scales and characterized, which did not cause any damage before this GMP manufacture process. The instant mitigation was to lower the pump rate to decrease the potential shear in the perfusion skid, given that the lower the pump rate, the lower chance to cause cell damage 12,13 . After reducing the flow rate, cell damage was subsequently avoided.…”

Ultra scale‐down characterization of the impact of conditioning methods for harvested cell broths on clarification by continuous centrifugation—Recovery of domain antibodies from rec E. coli

“…The level of the shear stress depends on the type of machine used (Boychyn et al, ). Shear stress is known to disrupt mammalian cells (Hutchinson et al, ; Kamaraju et al, ; Tait et al, ; Zaman et al, ), flocs (Berrill et al, ), and precipitates (Bell et al, ; Byrne et al, ; Hoare et al, ). Maybury et al () observed that there could be a 10–58% error in predicting the capacity of a continuous centrifuge if hydrodynamic stress equivalent to the conditions which prevail in the feed zone was not applied to the process material prior to centrifugation.…”